There are various surgical procedures that require fixing soft tissue to bone or bone to bone to produce healing such as fixing a bone flap or bone implant to a patient's skull. For example, craniotomies are surgical procedures conducted to treat various brain injuries, including tumors and aneurysms. As part of a craniotomy procedure, the surgeon creates an opening in the skull. One technique is to drill several adjacent holes to define the periphery of the opening and then using a tool to cut between the holes. The surgeon can either remove an entire section of the skull, or cut a sufficient amount to bend the skull away to allow access to the brain or head region. The cut-out section is commonly referred to as a bone flap. In other cases, an implant may be required to replace a section of the skull that is missing. In both cases, the bone flap or implant must be secured or fixed to the surrounding skull.
There are alternative ways to affix the bone flap or implant known to those in the art. One method involves drilling adjacent holes into the skull and into the bone flap or implant, and then securing the two together by way of threading a wire or other material through the holes and securing the ends of the material. Another fixation method uses bone plates to span the gap between the skull portion and the bone flap or implant. The bone plates contain screw holes through which screws are driven to secure the plate.
Another way to achieve fixation is to use metal clamps to span the gap between the skull and the bone flap or implant. The clamps commonly have a tube post with a first circular disk or plate secured to the bottom of the post. Another disk, having an annular center hole floats along the shaft of the post. The surgeon places the post between the skull and the bone flap or implant with the bottom plate below the skull and bone flap or implant and the other disk above those two pieces. An instrument is then used to hold the post and force the two plates together to secure the skull and bone flap or implant. The instrument usually has cutting blades on the end that first deform and then shear the post tube. An example of such a clamp system and an instrument for securing the clamps is described in WO 2006/066119.
The clamp system technique has many benefits over the other techniques, but there exists room for improvement of the instrument used to secure the clamps to the skull. The instrument should be easy to handle and not require excessive force to tension the clamp system or to shear the post tube.